Invoke a superclass method from a subclass constructor

Dave Angel davea at ieee.org
Sun Sep 11 13:55:31 CEST 2011


On 01/-10/-28163 02:59 PM, Kayode Odeyemi wrote:
> Hello friends,
>
> An instance of my subclass doesn't invoke its superclass method, except when
> it is referenced
> directly.
>
> Here is what I mean:
>
>>>> class A(object):
> ...     def log(self, module):
> ...             return str('logged')
> ...
>
>>>> class B(A):
> ...     def __init__(self, module):
> ...             self.module = A().log(module)
> ...
>>>> c = B('system')
>>>> # I expect 'logged' to be printed here
>>>> print c.log('system') # why do I have to do this?
>>>> 'logged'
> Why do I have to make a call to c.log before log() method can be invoked?
>
> My reasoning is such that since I have passed the log() method to B's
> constructor, an instance
> of B should invoke A's log() method.
>
> What could I be missing in class A or B to have this working as expected?
What makes you think that A.log() was not invoked???

You have no print statement, so you can't tell that way.  All the method 
does is to modify a temporary object of type A, so you can't tell that way.

Perhaps you mean to write
       self.module = A.log(self, module)

So that the return value could do some good.

DaveA




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